Wedding dedupe: preparation scene

There are three weddings scene files (single, double, and triple.) Triple is missing a LOT, and double is mostly a copy of single.

This "prep" scene is identical for the single slave in single, and for each of the slaves in double. Amazing that it hasn't diverged.

The most serious change I can remember making is moving to use seX(), so, pretty straight forward.

Edit: part of #3041 (closed)